0000000000088104
AUTHOR
Jacques Van Hoecke
showing 21 related works from this author
Effects of electromyostimulation versus voluntary isometric training on elbow flexor muscle strength.
2007
The purpose of this study was to determine whether 7 weeks of standardized (same number and duration of repetitions, sets and rest strictly identical) electromyostimulation training of the elbow flexor muscles would induce strength gains equivalent to those of voluntary isometric training in isometric, eccentric and concentric contractions. Twenty-five males were randomly assigned to an electromyostimulated group (EMS, n=9), a voluntary isometric group (VOL, n=8), or a control group (CON, n=8). Maximal voluntary isometric, eccentric and concentric strength, electromyographic (EMG) activity of the biceps and triceps brachii muscles, elbow flexor muscle activation (twitch interpolation techni…
Brain BDNF Levels Elevation Induced by Physical Training is Reduced after Unilateral Common Carotid Artery Occlusion in Rats
2014
International audience; We investigated the contribution of blood flow elevation in the cerebrovasculature to physical training-induced brain-derived neurotrophic factor (BDNF) levels elevation in the brain. Brain-derived neurotrophic factor protein levels were measured in the motor cortex 24 h after the last session of a forced treadmill walking (30 minutes a day, 18 m/minute for 7 consecutive days). Unilateral common carotid artery occlusion and modulation of exercise intensity (0 versus -10% inclination of the treadmill) were used as strategies to reduce the (normal) elevation of flow in the cerebrovasculature occurring during exercise. Administration of N-nitro-L-arginine methyl ester (…
Short-term changes in the series elastic component after an acute eccentric exercise of the elbow flexors
2001
We have studied the effect of a unique eccentric exercise session on the series elastic component (SEC) properties of human elbow flexors. Ten active females performed five sets of ten maximal eccentric contractions on an isokinetic ergometer. Maximal isometric (MVC) torque, and the corresponding myoelectrical activity (RMS) of the biceps brachii and the triceps brachii muscles were recorded before, immediately after, 48 h after, and 1 week after the exercise session. SEC compliance was also measured, using the in situ quick-release technique. Maximal eccentric torque declined significantly among the five sets of the exercise session (P < 0.01). The exercise session induced a significant de…
Comparison between voluntary and stimulated contractions of the quadriceps femoris for growth hormone response and muscle damage
2007
This study aimed to compare voluntary and stimulated exercise for changes in muscle strength, growth hormone (GH), blood lactate, and markers of muscle damage. Nine healthy men had two leg press exercise bouts separated by 2 wk. In the first bout, the quadriceps muscles were stimulated by biphasic rectangular pulses (75 Hz, duration 400 μs, on-off ratio 6.25–20 s) with current amplitude being consistently increased throughout 40 contractions at maximal tolerable level. In the second bout, 40 voluntary isometric contractions were performed at the same leg press force output as the first bout. Maximal voluntary isometric strength was measured before and after the bouts, and serum GH and blood…
Effects of joint angle and age on ankle dorsi- and plantar-flexor strength.
2007
This study aimed at examining the effects of joint angle and age on the maximal voluntary contraction (MVC) torque, for the agonist and antagonist muscle groups around the ankle, i.e., the dorsi- and plantar-flexors. To this aim, neural and muscular factors were investigated in two groups of healthy men: 11 young (mean age, 24 years) and 18 older (mean age, 78 years). Plantar-flexion (PF) and dorsiflexion (DF) isometric MVC torques were measured in three different ankle joint angles and surface electromyographic activities of the triceps surae and of the tibialis anterior muscles were recorded. The main findings were that the DF-to-PF MVC torque ratio varied with joint angle and age, indica…
Coactivation at the ankle joint is not sufficient to estimate agonist and antagonist mechanical contribution
2009
The aim of this study was to assess, via an elec- tromyographic (EMG) biofeedback method, the mechanical con- tribution of both agonist and antagonist muscles during maximal voluntary contraction (MVC). We compared this original method with the MVC-EMGmax ratio and the torque/EMG relationship method, both of which are commonly used to estimate antago- nist torque. The plantarflexion (PF) and dorsiflexion (DF) MVCs were measured simultaneously with EMG activity of triceps surae (TS) and tibialis anterior in 15 young adults (mean age 23 years). Antagonist torques obtained from the torque/EMG relationship and EMG biofeedback methods appeared to be similar. TS antagonist torque had a major mech…
Muscular performances at the ankle joint in young and elderly men.
2005
The effect of aging on mechanical and electromyographic characteristics of ankle joint muscles was investigated in 11 young (mean age 24 years) and 12 elderly (mean age 77 years) males. Maximal and submaximal isometric voluntary torques were measured during ankle plantarflexion and dorsiflexion. Electromyographic activities of triceps surae and tibialis anterior muscles were recorded. The elderly group developed equal maximal dorsiflexion torques (42 vs 45 N.m, p >.05), but in plantarflexion, the elderly group was weaker (80 vs 132 N.m, p <.001) and presented a decreased twitch amplitude (11 vs 16 N.m) and lower coactivation (8% vs 15%) than that of the young adults. We established a linear…
EMG activity and voluntary activation during knee-extensor concentric torque generation
2002
This study was designed to re-examine and compare the neural drive of the knee extensors during isokinetic concentric muscular actions by means of the twitch interpolation technique (activation level, AL) and surface electromyographic (EMG) recordings (root mean square, RMS). Torque, AL and RMS amplitudes of three knee extensors and one knee flexor were measured in nine subjects during maximal and sub-maximal voluntary contractions, performed under concentric (60 degrees.s(-1) and 120 degrees.s(-1); Con60 and Con120, respectively) and isometric (Iso) conditions. Mean (SD) maximal voluntary torque was significantly lower ( P0.01) during concentric contractions [Con60: 208.6 (26.8) Nm and Con…
Evidence of neuromuscular fatigue after prolonged cycling exercise
2000
International audience; Purpose: The purpose of this study was to analyze the effects of prolonged cycling exercise on metabolic, neuromuscular, and biomechanical parameters. Methods: Eight well-trained male cyclists or triathletes performed a 2-h cycling exercise at a power output corresponding to 65% of their maximal aerobic power. Maximal concentric (CON; 60, 120, 240°s 1), isometric (ISO; 0°s 1), and eccentric (ECC; 120,-60°s 1) contractions, electromyographic (EMG) activity of vastus lateralis (VL) and vastus medialis (VM) muscles were recorded before and after the exercise. Neural (M-wave) and contractile (isometric muscular twitch) parameters of quadriceps muscle were also analyzed u…
Effets d’une séance d’exercices excentriques sur la récupération à court terme de la contractilité musculaire
2000
Les effets a court terme de 5 series de 10 contractions maximales excentriques des flechisseurs du coude, realisees sur un ergometre isocinetique, sont etudies. Le moment maximal excentrique, isometrique, concentrique, l’activite myoelectrique des biceps et triceps brachii, le niveau d’activation volontaire, l’amplitude de la reponse M, l’amplitude de la secousse, les vitesses maximales de contraction et de relaxation sont mesures avant (Temoin), 2 minutes apres (Post), 24 heures (Post24h) et 48 heures (Post48h) apres la seance d’exercice.Le moment est significativement diminue de Temoin a Post48h, quel que soit le mode de contraction, excepte le moment concentrique mesure a 240°.s-l , qui …
Time of day effects on isometric and isokinetic torque developed during elbow flexion in humans
2001
The aim of this study was, firstly, to confirm or refute the existence of circadian rhythms during several velocities of concentric action of the elbow flexor muscles and, secondly, to compare the characteristics of these circadian rhythms with those obtained during isometric actions. Eight volunteer subjects participated in this study. The circadian rhythms were obtained from six test sessions (TS) carried out at different times of day over 6 days with only one TS a day. During each TS, oral temperature and the torque of the muscle action were measured. The subjects made, on an isokinetic ergometer, two maximal isokinetic concentric elbow flexions at five angular velocities (60, 120, 180, …
Changes in mechanical properties of human plantar flexor muscles in ageing
2003
Changes in contractile and elastic properties of human plantar flexor muscles in ageing, were investigated in 12 young (19-24 years, YG) and 11 old (61-74 year, OG) men. Maximal isometric and concentric voluntary torques, at several angular velocities, were measured to construct torque-angular velocity relationship. This led to the calculation of an index of maximal shorting velocity (VImax) at low torque. Two methods were then used to calculate musculotendinous (MT, quick-release movements) and musculoarticular (MA, sinusoidal perturbations) stiffness. In both cases, stiffness was linearly related to torque, leading to the calculation of a stiffness index (SI) as the slope of the stiffness…
Isokinetic elbow flexion and coactivation following eccentric training.
1999
The influence of an eccentric training on torque/angular velocity relationships and coactivation level during maximal voluntary isokinetic elbow flexion was examined. Seventeen subjects divided into two groups (Eccentric Group EG, n = 9 Control Group CG, n = 8) performed on an isokinetic dynamometer, before and after training, maximal isokinetic elbow flexions at eight angular velocities (from - 120 degrees s(-1) under eccentric conditions to 240 degrees s(-1) under concentric conditions), and held maximal and submaximal isometric actions. Under all conditions, the myoelectric activities (EMG) of the biceps and the triceps brachii muscles were recorded and quantified as the RMS value. Eccen…
Strength training in old age: adaptation of antagonist muscles at the ankle joint.
2005
The purpose of this study was to determine whether strength training could reduce the deficit in plantarflexion (PF) maximal voluntary contraction (MVC) torque observed in previous studies in older subjects relative to young adults. Accordingly, the effects of a 6-month strength training program on the muscle and neural properties of the major muscle groups around the ankle were examined. PF and dorsiflexion (DF) isometric MVC torques were measured and surface electromyographic activity of the triceps surae and tibialis anterior muscles was recorded. The strength training program was very effective in improving strength in PF (+24.5%), and it thus reduced the DF-to-PF MVC torque ratio; in a…
Concentric and/or Eccentric Training-Induced Alterations in Shoulder Flexor and Extensor Strength
1997
To examine the effect of specific concentric and eccentric training on muscular strength following an initial standardized period of excessive training, shoulder extensors and flexors were tested. The shoulder is a joint particularly susceptible to injury and requires a specific strength training program. For a period of 12 weeks, subjects performed training, including concentric and eccentric actions. Thereafter, they were divided into three groups that performed specific 12-week programs, including either concentric (C-E/C), eccentric (C-E/E), or a combination of both concentric and eccentric exercises (C-E/C-E). Following the initial period of training, significant increases (p0.05) in p…
Antagonist mechanical contribution to resultant maximal torque at the ankle joint in young and older men.
2007
Abstract A recorded muscular torque at one joint is a resultant torque corresponding to the participation of both agonist and antagonist muscles. This study aimed to examine the effect of aging on the mechanical contributions of both plantar- and dorsi-flexors to the resultant maximal voluntary contraction (MVC) torques exerted at the ankle joint, in dorsi-flexion (DF) and plantar-flexion (PF). The estimation of isometric agonist and antagonist torques by means of an EMG biofeedback technique was made with nine young (mean age 24 years) and nine older (mean age 80 years) men. While there was a non-significant age-related decline in the measured resultant DF MVC torque (−15%; p =0.06), there…
The relative contribution to the plantar-flexor torque of the soleus motor units activated by the H reflex and M response in humans.
2000
Abstract This study proposes a method of quantifying the relative contribution to the plantar-flexor torque of soleus H and M responses evoked by tibial nerve stimulation. For ten subjects, the amplitude of the twitch produced by the H wave was plotted against the corresponding potential, for stimuli producing H without M (i.e. in the ascending portion of the H-recruitment curve). It was then assumed that the contribution of H to twitches produced by M plus H was similar for similar H waves on the curve-descending portion. Hence, the contribution of M was estimated, for the range of M waves including those accompanying H max . The estimated mechanical contributions of H and M wave increase …
Difficult memory task during postural tasks of various difficulties in young and older people: A pilot study
2007
Abstract Objective This study examined the effects of a difficult and individually tailored additional cognitive task on postural stability and electromyographic (EMG) activities of the ankle dorsi- and plantar-flexors, in young and older individuals performing postural tasks of varying difficulties. Methods Eight young (mean age = 24 years) and eight older (74 years) men took part in the investigation. Centre of pressure velocity and surface EMG of ankle joint muscles were both examined during various postural conditions. Results The main findings suggested that high levels of muscle activity were a characteristic of age-related declines in postural stability. Moreover, during the complex …
Is backward disequilibrium in the elderly caused by an abnormal perception of verticality? A pilot study
2007
International audience; OBJECTIVE: We hypothesised that backward disequilibrium (BD), defined by a posterior position of the centre of mass with respect to the base of support, could be caused by a backward tilt in the perception of verticality. METHODS: The relationship between BD, the perception of verticality, and the history of falls in 25 subjects aged 84.5+/-7.4 years was analysed. An original ordinal scale, the BD scale (BDS), was used to quantify BD. Postural (PV) and haptic verticals (HV) were measured in sagittal plane. RESULTS: BDS scores closely correlated with the number of falls (r = 0.81, p =10(-5)). The more the PV was tilted backward, the greater the BDS scores (r = -0.95, …
Effects of a one-year exercise training program in adults over 70 years old: a study with a control group
2007
Background and aims: Exercise training is known to improve exercise tolerance in elderly subjects. Therefore the present study aimed at investigating the effects of one year of combined endurance and resistance training in healthy older people. Methods: After baseline evaluation, subjects were assigned to either the training group (n=24, age 77.2±3.6) or the control group (n=16, age 76.1±4.8). Subjects in the control group did not change anything in their everyday activities, whereas subjects in the training group underwent moderately intensive combined exercise training, 3 hours a week over the course of one year. Breath-by-breath oxygen uptake and heart rate were measured at each workload…
Activation of human quadriceps femoris during isometric, concentric, and eccentric contractions.
2001
Maximal and submaximal activation level of the right knee-extensor muscle group were studied during isometric and slow isokinetic muscular contractions in eight male subjects. The activation level was quantified by means of the twitch interpolation technique. A single electrical impulse was delivered, whatever the contraction mode, on the femoral nerve at a constant 50° knee flexion (0° = full extension). Concentric, eccentric (both at 20°/s velocity), and isometric voluntary activation levels were then calculated. The mean activation levels during maximal eccentric and maximal concentric contractions were 88.3 and 89.7%, respectively, and were significantly lower ( P < 0.05) with respe…